LeetCode/137_SingleNumber-2 at master · KnowledgeCenterYoutube/LeetCode · GitHub

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// C++:

int singleNumber(vector<int>& nums) {
        int ones = 0, twos = 0, thrice = 0;
        for(int n : nums){
            twos = twos | (ones & n);
            ones = ones ^ n;
            thrice = ones & twos;
            ones &= ~thrice;
            twos &= ~thrice;
        }
        return ones;
    }
// Java:

public int singleNumber(int[] nums) {
        int ones = 0, twos = 0, thrice = 0;
        for(int n : nums){
            twos = twos | (ones & n);
            ones = ones ^ n;
            thrice = ones & twos;
            ones &= ~thrice;
            twos &= ~thrice;
        }
        return ones;
    }

## Python3:

def singleNumber(self, nums: List[int]) -> int:
        ones, twos, thrice = 0, 0, 0
        for n in nums:
            twos = twos | (ones & n)
            ones = ones ^ n
            thrice = ones & twos
            ones &= ~thrice
            twos &= ~thrice

        return ones

Detailed Video Explanation is available here: https://youtu.be/ZbTXZ2_YAgI